Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W20/00—Interconnections in chips, wafers or substrates
  • H10W20/01—Manufacture or treatment
  • H10W20/031—Manufacture or treatment of conductive parts of the interconnections
  • H10W20/032—Manufacture or treatment of conductive parts of the interconnections of conductive barrier, adhesion or liner layers
  • H10W20/042—Manufacture or treatment of conductive parts of the interconnections of conductive barrier, adhesion or liner layers the barrier, adhesion or liner layers being seed or nucleation layers
  • H10W20/044—Manufacture or treatment of conductive parts of the interconnections of conductive barrier, adhesion or liner layers the barrier, adhesion or liner layers being seed or nucleation layers for electroless plating
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/18—Pretreatment of the material to be coated
  • C23C18/1803—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces
  • C23C18/1824—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment
  • C23C18/1837—Multistep pretreatment
  • C23C18/1844—Multistep pretreatment with use of organic or inorganic compounds other than metals, first
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/31—Coating with metals
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/40—Formation of materials, e.g. in the shape of layers or pillars of conductive or resistive materials
  • H10P14/46—Formation of materials, e.g. in the shape of layers or pillars of conductive or resistive materials using a liquid
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W20/00—Interconnections in chips, wafers or substrates
  • H10W20/01—Manufacture or treatment
  • H10W20/031—Manufacture or treatment of conductive parts of the interconnections
  • H10W20/032—Manufacture or treatment of conductive parts of the interconnections of conductive barrier, adhesion or liner layers
  • H10W20/042—Manufacture or treatment of conductive parts of the interconnections of conductive barrier, adhesion or liner layers the barrier, adhesion or liner layers being seed or nucleation layers
  • H10W20/0425—Manufacture or treatment of conductive parts of the interconnections of conductive barrier, adhesion or liner layers the barrier, adhesion or liner layers being seed or nucleation layers comprising multiple stacked seed or nucleation layers

Definitions

• the present invention relates to an electroless plating which allows an electroless plating layer used to form copper wiring on the surface being plated to be smooth, uniform and high-adhesion format, especially an electroless plating which is ideal for embedding fine vias or trenches formed on a semiconductor wafer without generating defects such as voids, seams or the like, and to a semiconductor wafer which is thus plated with the electroless plating.
• Electroless plating is one method of forming a metal coating film on an underlying material that does not possess conductivity; this technique is utilized in the formation of printed wiring on resin substrates and the like.
• a method known as activation in which a noble metal such as palladium or the like is adhered to the underlying material beforehand as a catalyst, is common pre-treatment for a semiconductor device in such electroless plating.
• methods have been used in which Pd is adhered by an immersion treatment in an aqueous solution of PdCl 2 following treatment with a hydrochloric acid aqueous solution of SnCl 2 , or in which Pd is supported on the surface by means of a colloidal solution containing Sn and Pd.
• the present invention unexpectedly discovered that the above-mentioned problems are solved by using a palladium compound, which is an electroless plating catalyst, in the form of an organic-solvent solution instead of the conventional aqueous medium. This discovery led to the perfection of the present invention.
• the present invention relates to:
• the present invention makes it possible to form a thin, defect-free, smooth and uniform electroless plating layer.
• the desired object of the present invention cannot be achieved even if the specified silane coupling agent used in the present invention is used.
• the functional group that is able to capture a metal that is useful in the present invention includes amino groups, carboxyl groups, azole groups, hydroxyl groups and mercapto groups, although the present invention is not limited to such groups. Among these groups, azole groups are especially desirable.
• azole groups include imidazole groups, oxazole groups, thiazole groups, selenazole groups, pyrazole groups, isooxazole groups, isothiazole groups, triazole groups, oxadiazole groups, thiadiazole groups, tetrazole groups, oxatriazole groups, thiatriazole groups, bendazole groups, indazole groups, benzimidazole groups and benzotriazole groups.
• imidazole groups are especially desirable.
• the above-mentioned silane coupling agent is a compound which has a —SiX 1 X 2 X 3 group in addition to the above-mentioned noble metal ion capturing group.
• X 1 , X 2 and X 3 each indicate an alkyl group, a halogen atom, an alkoxy group, and may be any functional groups that are capable of fixing to the substance being plated.
• X 1 , X 2 and X 3 may be the same or different.
• especially desirable compounds are silane coupling agents obtained by the reaction of an azole type compound and an epoxysilane type compound.
• compounds obtained by reacting with an imidazole compound as the azole compound may be cited as examples of especially desirable silane coupling agents.
• epoxysilane coupling agents expressed by the formula:
• R 1 and R 2 each are a hydrogen atom or an alkyl group with 1 to 3 carbon atoms, and n is 0 to 3) are desirable as epoxysilane type compounds in order to be reacted with such nitrogen-containing heterocyclic azole compounds.
• the reaction between said azole compound and said epoxy-group-containing silane compound can be performed under the conditions described in Japanese Patent Publication No. 6-256358.
• 0.1 to 10 moles of the epoxy-group-containing compound is added dropwise and reacted for 5 minutes to 2 hours with 1 mole of the azole compound at 80 to 200° C.
• a solvent there is no particular need for a solvent; however, an organic solvent such as chloroform, dioxanemethanol, ethanol or the like may also be used.
• reaction of the imidazole type compound and epoxysilane type compound indicated above as especially desirable examples is as follows:
• R 1 and R 2 each are a hydrogen atom or an alkyl group with 1 to 3 carbon atoms
• R 3 is a hydrogen atom or an alkyl group with 1 to 20 carbon atoms
• R 4 is a vinyl group or an alkyl group with 1 to 5 carbon atoms
• n is 0 to 3
• silane coupling agents with an ability to capture a metal examples include
• Examples of the aforementioned palladium compounds include chlorides, hydroxides, oxides, sulfates, amine complexes such as ammonium salts or the like of palladium which show a catalytic effect when copper, nickel, cobalt or the like is deposited on the surface of the substance to be plated from an electroless plating solution.
• Palladium chloride is especially desirable. It is necessary that the palladium compound be used in the form of an organic-solvent solution.
• organic solvents examples include methyl alcohol, ethyl alcohol, isopropanol, acetone, methyl ethyl ketone, toluene, ethylene glycol, polyethylene glycol, dimethylformamide, dimethyl sulfoxide and dioxane, as well as mixtures of these solvents. Furthermore, it is desirable that the concentration in the solution be 20 to 300 mg/L.
• the semiconductor wafers referred to in the present invention naturally include silicon wafers, and also include compound semiconductor wafers such as gallium-arsenic, gallium-phosphorus and indium-phosphorus wafers.
• the metal plating method of the present invention there are no restrictions on the material of the surface of the semiconductor wafer that is plated.
• a film of barrier metal with a low conductivity selected from a group consisting of titanium, tantalum, tungsten and nitrides of these metals formed by vacuum evaporation, sputtering or CVD constitutes the surface to be plated.
• the method of the present invention can be used effectively.
• the method of the present invention can be used efficiently.
• this liquid may be used by use of a solution of the agent dissolved in an appropriate solvent, e. g. water, methyl alcohol, ethyl alcohol, isopropanol, acetone, methyl ethyl ketone, toluene, ethylene glycol, polyethylene glycol, dimethylformamide, dimethyl sulfoxide or dioxane, as well as mixtures of these solvents.
• an appropriate solvent e. g. water, methyl alcohol, ethyl alcohol, isopropanol, acetone, methyl ethyl ketone, toluene, ethylene glycol, polyethylene glycol, dimethylformamide, dimethyl sulfoxide or dioxane, as well as mixtures of these solvents.
• the solution of the silane coupling agent is also more preferably used in the form of an organic-solvent solution.
• the solvent is volatilized following the coating of the surface by an immersion treatment.
• application by means of spin coating is desirable.
• concentration of the silane coupling agent with the functional group capable of capturing metals in the solution a concentration of 0.001 to 10 wt % is easy to use, although the present invention is not limited to such a concentration.
• concentration is less than 0.001 wt %, the amount of the compound that adheres to the surface of the substrate tends to drop, so that it is difficult to obtain an effect.
• the concentration exceeds 10 wt %, the amount of adhering compound is excessive, so that drying becomes difficult and the aggregation of powder tends to occur.
• the surface When the surface is dried following the surface treatment, it is sufficient to heat to a temperature exceeding the volatilization temperature of the solvent so that the solvent is volatilized; however, it is desirable to heat the surface for an additional 3 to 10 minutes at 60 to 150° C.
• the drying process can be omitted, and plating can be performed with only a water rinse following the surface treatment. In this case, however, a thorough water rinse must be conducted so that the catalyst is not carried into the plating solution.
• room temperature is sufficient; however, the rate and the amount of adhesion of the catalyst can be increased by heating. At the heating, a temperature of 30 to 80° C. is advisable.
• the surface to be plated may also be cleaned prior to the pre-treatment.
• treatment with a solution containing a reducing agent prior to plating is effective.
• treatment with a dimethylamine-borane solution or the like as a reducing agent is preferable.
• the present invention makes it possible to plate the surface of a semiconductor wafer with a metal such as copper, nickel, cobalt, tin or gold by electroless plating.
• a metal such as copper, nickel, cobalt, tin or gold
• vias or trenches used to embed the copper wiring are formed in the surface of the semiconductor wafer (consisting of silicon or the like), and the surfaces of these vias or trenches are covered to a thickness of approximately 0.01 to 0.1 ⁇ m with a barrier metal selected from a group consisting of titanium, tantalum, tungsten or nitrides of these metals by sputtering or CVD in order to prevent the copper from diffusing into the silicon.
• the surface of this barrier metal layer has been covered with a thin copper layer (seed layer) by sputtering or CVD in the same manner as described above.
• the above-mentioned barrier metal generally has a large electrical resistance, so that the difference of the current density between the central portions and the contact areas located in the peripheral of the wafer becomes large in the copper electroplating that is subsequently applied; accordingly, copper with a small electrical resistance is applied (as a thin covering) in advance.
• wiring is finer so that the diameters of vias and trenches are smaller, it becomes impossible to obtain sufficient coverage of the inside walls of such vias and trenches by using common conventional sputtering methods. This has led to the generation of defects (voids and seams) when the walls are subsequently electroplated.
• CVD methods on the other hand, the coverage is improved, but the cost is extremely high.
• a seed layer is formed by electroless plating with copper or nickel after a catalyst has been applied to the surface of the barrier metal by the above-mentioned pre-treatment method.
• This method makes it possible to solve the problem of inadequate coverage of the inside walls of vias and trenches of fine wiring at a lower cost than in the case of a CVD method.
• copper is applied by electroless plating, not only the formation of a seed layer, but also the embedding of wiring, can be accomplished by electroless plating by continuing the process.
• An alkali component is contained as a raw material in many electroless copper plating solutions and electroless nickel plating solutions.
• such an alkali component is a most undesirable impurity; accordingly, a raw material that does not contain this impurity must be used.
• tetramethylammonium hydroxide instead of the sodium hydroxide that is used to adjust the pH.
• dimethylamine-borane as the reducing agent in the electroless nickel plating solution.
• the formation of a barrier metal on the insulating film can also be accomplished by the electroless plating method of the present invention.
• Conceivable examples of the barrier metal in this case include nickel, cobalt and alloys of these metals with other metals (such as tungsten or the like).
• the formation of copper wiring can also be accomplished by the electroless plating method of the present invention.
• a plating layer with a thickness of 70 to 5000 angstroms and a mean surface roughness Ra of 10 to 100 angstroms, preferably a thickness of 100 to 3000 angstroms and a mean surface roughness Ra of 20 to 70 angstroms.
• a 0.02% isopropyl alcohol solution of a silane coupling agent that was an equimolar reaction product of imidazole and ⁇ -glycidoxypropyltrimethoxysilane was applied for 1 minute at 1000 rpm by means of a spin coater to a silicon wafer whose surface had been converted into SiO 2 by thermal diffusion. Following drying for 5 minutes at 100° C. by means of a drier, the coated wafer was cooled to room temperature, and an isopropyl alcohol solution of palladium chloride (Pd concentration: 60 mg/L) was applied for 1 minute at 1000 rpm by means of a spin coater. Following drying for 5 minutes at 100° C.
• Pd concentration palladium chloride
• the sample was cooled to room temperature, and was immersed in an electroless nickel plating solution, so that electroless nickel plating was performed.
• the nickel plating film thus obtained showed good adhesion.
• the thickness of the nickel film was 400 angstroms (Both figures were converted with SiO 2 ).
• the mean roughness Ra was 62 angstroms.
• a 0.02% isopropyl alcohol solution of a silane coupling agent that was an equimolar reaction product of imidazole and ⁇ -glycidoxypropyltrimethoxysilane was applied for 1 minute at 1000 rpm by means of a spin coater to a silicon wafer whose surface had been converted into SiO 2 by thermal diffusion. Following drying for 5 minutes at 100° C. by means of a drier, the coated wafer was cooled to room temperature, and an isopropyl alcohol solution of palladium chloride (Pd concentration: 60 mg/L) was applied for 1 minute at 1000 rpm by means of a spin coater. Following drying for 5 minutes at 100° C.
• Pd concentration palladium chloride
• the sample was cooled to room temperature, and was immersed in an electroless nickel plating solution, so that electroless nickel plating was performed; then, the sample was electroless plated with copper.
• the copper plating film thus obtained showed good adhesion.
• the thickness of the nickel film was 700 angstroms, and that the thickness of the copper film was 2000 angstroms (Both figures were converted with SiO 2 ).
• the mean roughness Ra was 53 angstroms.
• a 0.022% methyl ethyl ketone solution of a silane coupling agent that was an equimolar reaction product of imidazole and ⁇ -glycidoxypropyltrimethoxysilane was applied for 1 minute at 1000 rpm by means of a spin coater to a silicon wafer whose surface had been converted into SiO 2 by CVD. Following drying for 5 minutes at 100° C. by means of a drier, the coated wafer was cooled to room temperature, and a methyl ethyl ketone solution of palladium chloride (Pd concentration: 60 mg/L) was applied for 1 minute at 1000 rpm by means of a spin coater. Following drying for 5 minutes at 100° C.
• the sample was cooled to room temperature, and was immersed in an electroless nickel plating solution, so that electroless nickel plating was performed; then, the sample was electroless plated with copper.
• the copper plating film thus obtained showed good adhesion.
• the thickness of the nickel film was 1200 angstroms, and that the thickness of the copper film was 600 angstroms (Both figures were converted with SiO 2 ).
• the mean roughness Ra was 51 angstroms.
• a 0.02% methanol solution of a silane coupling agent that was an equimolar reaction product of imidazole and ⁇ -glycidoxypropyltrimethoxysilane was applied for 1 minute at 1000 rpm by means of a spin coater to a silicon wafer whose surface had been converted into SiO 2 by thermal diffusion. Following drying for 5 minutes at 100° C. by means of a drier, the coated wafer was cooled to room temperature, and a methanol solution of palladium chloride (Pd concentration: 100 mg/L) was applied for 1 minute at 1000 rpm by means of a spin coater. Following drying for 5 minutes at 100° C.
• the sample was cooled to room temperature, and was immersed in an electroless copper plating solution so that electroless copper plating was performed.
• the copper plating film thus obtained showed good adhesion.
• the thickness of the copper film was 400 angstroms (Both figures were converted with SiO 2 ).
• the mean roughness Ra was 43 angstroms.
• a 0.02% isopropyl alcohol solution of a silane coupling agent that was an equimolar reaction product of imidazole and ⁇ -glycidoxypropyltrimethoxysilane was applied for 1 minute at 1000 rpm by means of a spin coater to a silicon wafer whose surface had been converted into SiO 2 by thermal diffusion.
• the coated wafer was cooled to room temperature, and a aqueous solution of palladium chloride (Pd concentration: 60 mg/L) was applied for 1 minute at 1000 rpm by means of a spin coater.
• the sample was cooled to room temperature, and was immersed in an electroless nickel plating solution, so that electroless nickel plating was performed. The areas that were not plated remained on the wafer.
• Isopropyl alcohol was applied for 1 minute at 1000 rpm by means of a spin coater to a silicon wafer whose surface had been converted into SiO 2 .
• the coated wafer was cooled to room temperature, and an aqueous solution of palladium chloride (Pd concentration: 60 mg/L) was applied for 1 minute at 1000 rpm by means of a spin coater.
• the sample was cooled to room temperature, and was immersed in an electroless nickel plating solution, so that electroless nickel plating was performed. The surface of the wafer was not plated at all.
• An isopropyl alcohol solution of palladium chloride (Pd concentration: 60 mg/L) was applied for 1 minute at 1000 rpm by means of a spin coater to a silicon wafer whose surface had been converted into SiO 2 . Following drying for 5 minutes at 100° C. by means of a drier, the coated wafer was cooled to room temperature, and was immersed in an electroless nickel plating solution, so that electroless nickel plating was performed. The surface of the wafer was not plated at all.
• the compound in the method of the present invention, as described above, by a palladium compound which is a catalyst is used in the from of an organic-solvent solution, the compound can therefore be uniformly fixed to even semiconducting mirror-surfaces such as semiconductor wafers an to the inside wall of vias and trenches formed on such a surface.
• electroless plating can easily be performed although such coverage has been difficult in the past.
• a suitable metal thin film can be formed smoothly, uniformly and with good adhesion as a seed layer on the surface of a semiconductor wafer.

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• 2003
  • 2003-03-26 JP JP2003587998A patent/JPWO2003091476A1/ja active Pending
  • 2003-03-26 KR KR1020037011990A patent/KR100560268B1/ko not_active Expired - Lifetime
  • 2003-03-26 CN CNB038001721A patent/CN100348775C/zh not_active Expired - Lifetime
  • 2003-03-26 WO PCT/JP2003/003707 patent/WO2003091476A1/fr not_active Ceased
  • 2003-03-26 EP EP03747201.6A patent/EP1498511B1/fr not_active Expired - Lifetime
  • 2003-03-26 US US10/472,678 patent/US7179741B2/en not_active Expired - Lifetime
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